Move kernel baseline tests to front_end.

pkg/front_end/test/fasta/rasta/issue_000053.dart

-// Copyright (c) 2016, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE.md file.
-
-class C {
-  operator ==(other) => throw 'x';
-  test() {
-    super == null;
-  }
-}
-main() {
-  new C().test();
-}